California sycamore (Platanus racemosa) is an iconic native tree species found in California and northern Baja California. The health and regeneration of California sycamore have been substantially affected by a wide range of factors, including hydrologic modifications of creeks, hybridization with London plane tree (Platanus x hispanica), and anthracnose. San Francisco Estuary Institute and H. T. Harvey & Associates conducted a study to develop a better understanding of the biotic and abiotic factors that influence California sycamore health and regeneration. The study investigated the relative distribution, health, and regeneration patterns of two major stands of sycamore alluvial woodland (SAW) in southern Santa Clara County, representing managed and natural settings. Specifically, we asked: what site characteristics are most favorable to the health and reproduction of SAW? Our data suggest that:
- in general, healthier and living sycamores are located closer to the creek channel than dead or unhealthy trees;
- natural hydrographs alone do not guarantee healthy regeneration, but flooding is necessary; and
- regeneration success may be negatively affected by anthracnose and herbivory.
Future studies will work to characterize the nature of hybridization between California sycamore and London plane tree in southern Santa Clara County and to locate California sycamore individuals that can be used as propagule sources for a propagation study. The propagation study will aim to identify reliable and cost-effective techniques to vegetatively propagate California sycamore. The results of these studies will advance the understanding of California sycamore ecology and the science of restoring California sycamore habitats.
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Sycamore Alluvial Woodland Habitat Mapping and Regeneration Study (Project)
Sycamore alluvial woodland in Palassou Ridge. Photo credit: Amy Richey
This study investigates the relative distribution, health, and regeneration patterns of two major stands of sycamore alluvial woodland (SAW) in Santa Clara County, representing managed and natural settings. Using an array of ecological and geomorphic field analyses, we, along with our partners at H.T. Harvey, discuss site characteristics favorable to SAW health and regeneration, make recommendations for restoration and management, and identify next steps.